Microwave oven



FIG. 1 is a front perspective view of a microwave oven showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof; and,

FIG. 5 is a left side elevational view thereof. 

The ornamental design for a microwave oven, as shown and described. 